50mm f/1.8 with Extension Tubes or 70-200 f/2.8 with Close Up Lens

So basically i have the Canon 50mm f/1.8 and the Tamron 70-200mm f/2.8 VC.

From what I've read, extension tubes work best for smaller focal lengths and close up lens work best for telephoto lens. So purely for macro shots - insects/flowers, which would be the more preferable setup?